Cartilage (hyaline cartilage or articular cartilage) is a 3-5 mm thin tissue that coats the boney surfaces inside joints, as well as forms other lubricating strong surfaces. It provides a very low friction articulation that ideally lasts a life time. Cartilage may be damaged through acute injury or degeneration over time. For example, osteoarthritis (OA) is a joint disorder that leads to thinning of cartilage and progressive joint damage. Nearly 40 percent of Americans over the age of 45 have some degree of knee OA, and those numbers are expected to grow as the population ages. Focal lesions of articular cartilage can progress to more widespread cartilage destruction and arthritis that is disabling. Articular cartilage has a limited intrinsic ability to heal. For this reason, orthopedic management of these lesions remains a persistent problem for the orthopedist and patient. The importance of treating injury to cartilage is underscored by the fact that several million people are affected in the United States alone by cartilage damage (Praemer A, et al. American Academy of Orthopaedic Surgeons 1999 p. 34-9).
Depending on the size and location of a cartilage defect, various surgical procedures are performed for cartilage repair including debridement, abrasion arthroplasty, microfracture, osteochondral autograft transfer, osteochondral allograft transplantation, and autologous chondrocyte implantation (Browne J E, et al. Clinical Orthopaedics and Related Research 2005; 436:237-245; Magnussen R A, et al. Clinical Orthopaedics and Related Research 2008; 466:952-96).
However, restoring a normal cartilaginous surface and improving integration with surrounding normal articular cartilage are highly challenging. Studies have shown implanting fully functional cartilage into defects, such as osteochondral auto- and allografts, often results in poor integration to the surrounding cartilage tissue (Hunziker E B. Osteoarthritis Cartilage. 2002; 10:432-463). Previous biomaterial implants have not succeeded in clinical and preclinical studies, owing to poor integration and the promotion of bone and fibrous tissue growth instead of hyaline cartilage, as is often seen with rigid materials in vivo (Custers R J, et al. J Bone Joint Surg Am. 2009; 91:900-910.).
Therefore, it is an object of the present invention to provide a biocompatible gel composition for good adhesion and integration with cartilage tissue and controlled delivery of therapeutic agents.
It is another object of the present invention to provide a method of treating and preventing cartilage damage.